Este trabalho propõe um método de análise do trade-off entre o buffer de capacidade de produção e o buffer de estoque, necessários para garantir o bom desempenho de um sistema sujeito a variações de demanda. A análise envolve a definição de um sistema de produção e a construção de um modelo de simulação. A simulação é realizada num sistema formado por uma única estação de trabalho, com mix de 10 produtos, controlados por um sistema kanban, que é considerado por muitos autores inadequado para operar em ambientes cuja demanda não é estável. Os resultados mostram que o buffer de capacidade proporciona vantagens operacionais e de custo ainda que sujeito a maiores níveis de variação de demanda. / This research proposes a method to analyze the trade-off between the production capacity buffer and the inventory buffer, required to guarantee high performance levels in a system with demand variation. The analysis involves a production system delineation and the development of a simulation model. The system simulated is a single-stage production system, with mix of ten products, controlled by a kanban system, which is classified by several authors as not recommended in environments with unstable demand. The results indicate that the production capacity buffer enables operational and cost advantages, even if the production system is under higher demand variation.

Spintronics discusses about fundamental physics and material science in mostly nanometer size structures. Spintronics also delivers many promising technologies for now and the future. One of the interesting spintronic structures is called “Magnetic Tunnel junction” (MTJ). A typical MTJ consists of a thin (1-3nm) insulator layer sandwiched between two ferromagnetic layers. In this work, I present MTJ with perpendicular magnetic anisotropy (PMA) using an MgO tunnel barrier. The effect of different heavy metals (HMs) adjacent to the ferromagnets (FMs) on tunneling magnetoresistance (TMR) and PMA of the junctions are discussed. Namely, Ta, Mo, Ta/Mo, W, Ir, and Hf have been utilized in HM/FM/MgO structures, and magneto-transport properties are explored. It is shown that when Ta/Mo is employed, TMR values as high as 208%, and highly thermally stable PMA can be obtained. Some physical explanation based on electronic band structure and thermochemical effects are discussed. In the last part of this work, the newly discovered tunneling anisotropic magnetoresistance (TAMR) effect in antiferromagnets is studied, and clear TAMR is demonstrated for NiFe/IrMn/MgO/Ta structures.

Submitted by Sandra Maria Neri Santiago (sandra.neri@ufpe.br) on 2016-04-14T14:13:25Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO - Thalianne de Andrade Leal.pdf: 2510019 bytes, checksum: 2da7c82c8d63d8018e80a8e30f841238 (MD5) / Made available in DSpace on 2016-04-14T14:13:25Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO - Thalianne de Andrade Leal.pdf: 2510019 bytes, checksum: 2da7c82c8d63d8018e80a8e30f841238 (MD5) Previous issue date: 2011-06-30 / O rápido e intenso desenvolvimento urbano atual vem impondo ao campo da Conservação dos monumentos novas inquietações. A tentativa de conciliação entre arquitetura contemporânea, a integridade dos monumentos e o desenvolvimento urbano está presente na pauta de especialistas preocupados com o impacto de novas estruturas sobre as heranças urbanas. Aos bens inscritos ou tombados pelos órgãos da preservação já são garantidas medidas de salvaguarda, com isso a preocupação foca-se em seu entorno. Apesar da recorrente indicação de que o entorno é parte importante para a compreensão das informações do bem ao contribuir com a manutenção da sua integridade, poucas medidas o definiram conceitualmente e não chegaram a efetivar uma metodologia que possibilitasse sua delimitação. A partir da discussão dos conceitos e de experiências de delimitação do entorno, foi adotada neste trabalho a investigação sobre as dificuldades que tardam a sua efetividade como ferramenta do campo da Conservação. Optou-se por focar no entorno de bens arquitetônicos situados em território urbano, opção esta que ligou à discussão ao território das cidades, aos seus atores, instrumentos normativos e interesses. Sendo o ambiente urbano alvo de constantes mudanças e permanências, a efetividade do entorno parte do acompanhamento das tendências para alteração da composição morfológica e dos seus atributos ao longo do tempo, os quais têm interferência sobre a continuidade na transmissão das informações dos bens. Interesses diversos sobrepõem-se nas cidades, e muitos deles dificultam as ações da Conservação. São destacadas também as dificuldades de integração entre instituições e instrumentos para a utilização da ferramenta. Compreendidas as dificuldades e sanadas as lacunas, o entorno pode efetivar-se como uma ferramenta auxiliar contra as investidas de modificações na proximidade de monumentos e contribuir para a manutenção da sua integridade. / Actually, the rapid and intense urban development has imposing on the field of monuments conservation new concerns. The attempt to reconcile contemporary architecture, the monuments integrity and urban development is present on the staff of specialists concerned with the impact of new structures on urban heritage. To property protected are warranted preservation measures, thus the concern focuses on his buffer zones. Despite the applicant's statement that the environment is an important part to understand the property information to contribute to the maintenance of its integrity, few measures have defined conceptually and failed to effect a methodology that would enable its boundaries. From the discussion of concepts and experiences of defining the buffer zone, was adopted in this research work on the difficulties that are delaying its effectiveness as a tool in the field of Conservation. We chose to focus on the buffer zone architectural property located in urban territory, that option is called to discuss the territory of the cities, its actors, instruments and regulatory interests. As the urban environment subject to constant change and permanence, the effectiveness of the buffer zone focus of the monitoring of trends and morphological change in the composition of its attributes over time, which have interference on the continuous transmission of property information’s. Diverse interests overlap in the cities, and many hinder the Conservation actions. Are also highlighted the difficulties of integration between institutions and instruments for the use of the tool. Understood the difficulties and shortcomings remedied, the buffer zone can manifest itself as an auxiliary tool against the onslaught of changes in the monuments surroundings and contribute to the maintenance of its integrity

When elephants leave primary protected areas (PPAs), such as national parks and game reserves, they may come into conflict with people residing on the adjoining land. In this study, I attempted to determine why African savannah elephants leave the PPAs in which they were collared. To accomplish this, I used telemetry locations of collared elephants in PPAs throughout southern Africa and investigated whether a range of intrinsic and extrinsic variables could explain why elephants crossed the boundaries of the PPAs. Adjoining many of the PPAs were secondary protected areas (SPAs), which consisted of community conservancies, and collectively with the PPAs formed clusters of protected areas. Most (45 of 49) elephants roamed beyond the PPAs but they remained within the clusters of protected areas. The elephants utilised both the PPAs and the SPAs and appeared to not feel threatened when using the SPAs. The reasons for elephants leaving PPAs varied both seasonally and between the sexes. The females roamed beyond the PPAs more during the wet season than the dry season, whereas, for males there was no seasonal difference. During the wet season, female and male habitat selection was similar within and beyond the PPAs. During the dry season, more females and males beyond the PPAs selected for areas close to people, which could be indicative of water. The proportion of male and female home ranges beyond PPAs did not increase with increasing density of elephant populations within the PPAs, nor did the proportion of female home ranges beyond PPAs increase with increasing population growth rate of elephant populations within the PPAs. Therefore, high numbers of elephants within the PPAs did not drive elephants beyond the boundaries. Contrastingly, the proportion of male home ranges beyond the PPAs did increase with increasing population growth rate. However, the results were inconclusive due to small sample size. This study confirms that elephants are utilising the SPAs as well as the PPAs. Therefore, the importance of including the SPAs in conservation actions for elephants cannot be over-emphasized. / Dissertation (MSc)--University of Pretoria, 2013. / Zoology and Entomology / unrestricted

Riparian buffers have been created as a sustainable and effective way to combat the harmful effects of excess nitrogen and soil salinity in riparian settings. The goal of this research was to determine what species will I) germinate in saline environments and II) establish and produce sufficient biomass while being exposed to increased nitrogen. Incubation of eight native riparian graminoid species were evaluated for their ability to germinate in MgSO4-induced salinity. In a greenhouse study, seven riparian graminoid species were evaluated to quantify their ability to survive and take up nitrogen, mimicking buffer strips exposed to high inputs of runoff nitrogen. Slender wheatgrass and green needlegrass were able to germinate successfully when exposed to MgSO4 with EC levels up to 16 dS m-1 and 8 dS m-1, respectively. Of the graminoid species tested, smooth brome yielded sufficient biomass and nitrogen uptake percentages in a controlled setting.

Industrial Development Centre (IUC) in Olofström inc. has constructed a measurement value logger which can sample values from eight channels, buffer them and then send them wireless with the Bluetooth technology to e.g. a computer.</p> In this thesis the data transfer rate, i.e. the number of values per second has been studied for different logger settings and when there are interferences in the Bluetooth traffic. How Bluetooth is affected by interferences has been studied with a number of experiments performed at IUC's RF-damped Faraday's cage. The thesis provides a model for this Bluetooth logger. The model extends the existing simulation system NS2-UCBT with a 'logger protocol'. NS2-UCBT was also extended to better support modeling of losses (due to Bluetooth channel impairments) and for the model of these losses to be based on experiments. The resulting simulation program allows developers to construct and evaluate a measurement system utilizing such a Bluetooth logger. Using the simulation model, the data rate measured in samples per second was examined for the logger. The simulations shows that optimizing the logger's configuration will improve that data rate considerable. This report contains: a summary of the problem and earlier research, an explanation of the simulation system and the simulation program, comparisons between simulations and experiments, some conclusions, and proposes future work in this area. / Industriellt Utvecklings Centrum (IUC) i Olofström AB har tagit fram en mätvärdeslogger som kan sampla värden från åtta kanaler, mellanlagra dem och skicka dem till exv. en dator trådlöst med Bluetooth teknologin. I det här examensarbetet har överföringshastigheten, dvs antal mätvärden per sekund studerats för olika inställningar på loggern och då det förekommer störningar i Bluetooth trafiken. Hur Bluetooth påverkas av störningar har undersökts genom en rad experiment i IUC's RF-dämpade skärmlabb. Arbetet har lett fram till en modell för mätvärdesloggern och ett simuleringsprogram som gör det möjligt för utvecklare att konstruera och utvärdera sina mätsystem med mätvärdes logger. Modellen använder det befintliga NS2-UCBT simuleringssystemet utvidgat med ett 'logger protokoll', mer utvecklad förlusthantering än NS2-UCBT i grundutförandet erbjuder och flexibel förlusthantering baserad på experiment. Med simuleringsmodellen undersöktes loggerns datahastighet i sampel per sekund. Simuleringarna visa att genom att förbättra loggerns konfiguration kan avsevärt högre datahastighet nås. Den här rapporten innehåller: en sammanfattning av problemställningen och tidigare forskning, en beskrivning av simulationssystemet och simulationsprogrammet, jämförelser mellan simuleringar och experiment, en del slutsatser, och förslag på framtida arbete i området.

Out-of-Core simulation systems often produce a massive amount of data that cannot t on the aggregate fast memory of the compute nodes, and they also require to read back these data for computation. As a result, I/O data movement can be a bottleneck in large-scale simulations. Advances in memory architecture have made it feasible and a ordable to integrate hierarchical storage media on large-scale systems, starting from the traditional Parallel File Systems (PFSs) to intermediate fast disk technologies (e.g., node-local and remote-shared NVMe and SSD-based Burst Bu ers) and up to CPU main memory and GPU High Bandwidth Memory (HBM). However, while adding additional and faster storage media increases I/O bandwidth, it pressures the CPU, as it becomes responsible for managing and moving data between these layers of storage. Simulation systems are thus vulnerable to being blocked by I/O operations. The Multilayer Bu er System (MLBS) proposed in this research demonstrates a general and versatile method for overlapping I/O with computation that helps to ameliorate the strain on the processors through asynchronous access. The main idea consists in decoupling I/O operations from computational phases using dedicated hardware resources to perform expensive context switches. MLBS monitors I/O tra c in each storage layer allowing fair utilization of shared resources. By continually prefetching up and down across all hardware layers of the memory and storage subsystems, MLBS transforms the original I/O-bound behavior of evaluated applications and shifts it closer to a memory-bound or compute-bound regime. The evaluation on the Cray XC40 Shaheen-2 supercomputer for a representative I/Obound application, seismic inversion, shows that MLBS outperforms state-of-the-art PFSs, i.e., Lustre, Data Elevator and DataWarp by 6.06X, 2.23X, and 1.90X, respectively. On the IBM-built Summit supercomputer, using 2048 compute nodes equipped with a total of 12288 GPUs, MLBS achieves up to 1.4X performance speedup compared to the reference PFS-based implementation. MLBS is also demonstrated on applications from cosmology, combustion, and a classic out-of-core computational physics and linear algebra routines.

As the functionality that current computer network can provide is becoming complicated, a traditional router with application-specific integrated circuit (ASIC) implementation can't satisfy the flexibility requirements. Instead, a programmable packet forward system based on a general-purpose processor could provide the flexibility. While this system provides flexibility, a new potential security issue arises. Usually, software is involved as the packet forward system is programmable. The software's potential vulnerability, especially as to the remote exploits, becomes an issue of network security. In this thesis work, we proposed a software stack overflow vulnerability on click modular router and show how a disastrous denial-of-service attack on click modular router could be triggered by a single packet. In our research work, click modular router runs on Linux operating system based on general-purpose hardware. We actually showed that even a software router run within a modern operating system's protection is vulnerable by elaborate attack. And we checked the possible stack protection mechanisms on modern OS based on general-purpose hardware and proposed a possible stack protection mechanism for embedded OS.

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